Characterization of melanocortin receptor subtype expression in murine adipose tissues and in the 3T3-L1 cell line

Bruce A. Boston, Roger D. Cone

Research output: Contribution to journalArticle

171 Scopus citations

Abstract

It has been known for many years that adipocytes express high affinity ACTH and α-melanocyte stimulating hormone (MSH) binding sites, and that ACTH, α-MSH, and β-lipotropin are potent lipolytic hormones. We show here that the adipocyte response to the melanocortin peptides results from the expression of both the MC2 (ACTH) receptor as well as the newly discovered MC5 receptor. Using RT-PCR and Northern blot hybridization, high levels of MC2 receptor messenger RNA (mRNA) were found in all adipose tissues examined in the mouse, whereas MC5 receptor mRNA was found in a subset of these. Both receptor mRNAs were also found in the 3T3-L1 cell line but only after the cells had been induced to differentiate into adipocytes. This cell line was then used to characterize the pharmacological properties of the MC2 and MC5 receptor sites in situ. The MC2 receptor exhibits properties similar to the ACTH receptor characterized in adrenocortical cells, coupling to activation of adenylyl cyclase with an EC50 of approximately 1 nM. An MSH binding site characterized in these cells is presumably the MC5 receptor, based on the observation that this is the only other melanocortin receptor mRNA detected in these cells. The MC5 receptor in the 3T3-L1 adipocyte activated adenylyl cyclase in response to α-MSH stimulation. Interestingly, Nle4, D-Phe7-α- MSH (NDP-MSH), a commonly used synthetic α-MSH agonist, was a potent antagonist of the MC5 receptor expressed in the 3T3-L1 cell line. Although the agouti signaling peptide is a potent antagonist of NDP-MSH binding to the MC1 and MC4 melanocortin receptors, agouti was unable to block NDP-MSH binding in the 3T3-L1 adipocyte.

Original languageEnglish (US)
Pages (from-to)2043-2050
Number of pages8
JournalEndocrinology
Volume137
Issue number5
DOIs
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Endocrinology

Fingerprint Dive into the research topics of 'Characterization of melanocortin receptor subtype expression in murine adipose tissues and in the 3T3-L1 cell line'. Together they form a unique fingerprint.

  • Cite this